Narrow-aisle truck with retractable arms

ABSTRACT

A narrow-aisle lift truck with a wheelbase which can be varied by hydraulic cylinders operable to extend and retract movable arms upon which are mounted nonsteerable wheels.

United States Patent Walter M. Shaffer Chesterland; John T. Crawford, Lyndhurst, both of Ohio 822,843

Apr. 14, 1969 Nov. 2, 1971 Towmotor Corporation Cleveland, Ohio Inventors Appl. No. Filed Patented Assignee NARROW-AISLE TRUCK WITH RETRACTABLE ARMS 7 Claims, 7 Drawing Figs.

U.S. Cl 214/730, 280/34 Int. Cl 866i 9/14 [50] Field of Search 214/670, 671, 672, 673, 674, 730; 187/9; 280/34 R, 34 A [56] References Cited UNITED STATES PATENTS 1,799,307 4/1931 Manley 280/34 UX 2,320,601 6/1943 Howell 214/670 X 2,851,182 9/1958 Gehring 214/730 Primary Examiner-Robert G. Sheridan Attorney-Fryer, Tjensvold, Feix, Phillips & Lempio ABSTRACT: A narrow-aisle lift truck with a wheelbase which can be varied by hydraulic cylinders operable to extend and retract movable arms upon which are mounted nonsteerable wheels.

PATENIEUNUVZ nan "3,516,953

vamateur 4 INVENTORS WALTER M. SHAFFER JOHN T. CRAWFORD 9.; j yla l BACKGROUND AND SUMMARY OF THE INVENTION In warehousing, profit is directly related to the versatility and capacity of the storage space available. In other words, the more material which can be gotten into a warehouse, the more profitable the warehouse becomes. In light of this, it is easily seen that the aisles in a warehouse must be considered to be nonproductive since nothing can be stored in them. For this reason, many attempts have been made in recent years to produce lift trucks which could operate in the narrowest possible space so as to minimize the floor space in a warehouse which must be devoted to aisles.

Other types of existing narrow-aisle trucks include straddlebase trucks with front outrigger members having such dimensions to permit straddling the load to be picked up, and trucks containing a pantograph mechanism for reaching beyond the forward outrigger wheels to engage the load. When aisle width is not critical, a counterbalanced truck is normally used, wherein the front of the mast is always located ahead of the front wheels, and counterbalancing weight is applied behind the front wheels for stability.

The subject invention readily fulfills the requirement of operating in the narrowest possible aisle space with the stability of a counterbalanced truck and without the disadvantages of the existing narrow-aisle trucks. For example, reach mechanisms have visibility limitations and high maintenance costs; both reach trucks and straddle trucks have exposed operator compartments which constitute a safety hazard and, in addition, have poor accessibility to the electric storage bat tery.

The subject invention accomplishes the sought-after requirement by providing a variable wheelbase which may be changed for any given size load. The wheelbase is varied by means of hydraulically extending and retracting two of the vehicle wheels along the longitudinal axis of the vehicle. Additionally, the provision of an extended wheelbase produces improved stability when transporting loads.

Thus, it is an object of this invention to provide a lift truck which increases warehouse versatility, safety and capacity.

It is also an object of this invention to provide a lift truck capable of operating in a narrower aisle than heretofore possible while providing counterbalanced truck advantages.

It is also an object of this invention to provide such a lift truck having a variable wheelbase which provides stability and versatility equal to that of machines having longer wheelbases, but which must operate from much wider aisles.

It is a further object of this invention to provide a lift truck having a variable wheelbase, allowing optimum side angle stacking in narrower aisles than with those trucks presently available.

It is a still further object of this invention to provide a variable wheelbase lift truck which permits a long wheelbase during normal operation of the vehicle, thereby providing proper location and protection of the driver and the battery compartment.

It is a still further object of this invention to provide a lift truck which eliminates the well-known reach mechanism which has many moving parts, thereby decreasing maintenance costs.

It is also an object of this invention to provide a lift truck having a turning radius which is much smaller than those of counterbalanced lift trucks presently available.

Other objects and advantages of the present invention will become apparent from the following description and claims as illustrated in the accompanying drawing which, by way of illustration shows a preferred embodiment of the present invention and principles thereof and what is now considered to be the best mode contemplated for applying these principles. It is recognized that other embodiments of the invention utilizing the same or equivalent principles may be used, and structural changes may be made as desired by those skilled in the art, without departing from the present invention and purview of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a lift truck utilizing the present invention;

FIG. 2 is a side elevation view of the lift truck shown in FIG.

FIG. 3 is a front elevation, partly in section, of the lift truck shown in FIGS. 1 and 2; and

FIGS. 4-7 illustrate plan views of the lift truck embodying the present invention, and the manner in which it is used to place a load in position.

DETAILED DESCRIPTION Referring now to FIGS. 1-3 in greater detail, there is shown a lift truck 10 having an operator's compartment 12, to the rear of which is a large compartment 14 which contains the vehicle batteries and motor or an engine.

A pair of steerable drive wheels 18 are mounted on the vehicle below the compartment 14, the wheels beingsteerable by any well-known mechanism (not shown).

On the forward portion of the vehicle, a mast pivot support 20 carries a mast 22 which is pivotable about bearings 24. Also on the forward portion of the vehicle, a sideshifter carriage 28 carries a pair of load forks 30.

A pair of nonsteerable load wheels 32 are mounted on movable arms 34 which are of a channel cross section. As clearly shown in FIGS. 1 and 2, the nonsteerable load wheels are in the extended position. When retracted, the axes of the wheels are withdrawn to the left until their axes are nearly on a vertical line drawn from the axes of the bearings 24.

A pair of guide rollers 36 are mounted in fixed relationship to the lift truck 10, and a pair of movable guide rollers 38 are mounted on the rear end of the movable arm assembly 34.

A hydraulic cylinder 40, on each side: of the truck, is utilized to extend and retract the arm assembly 34. When the arm assembly is retracted, the wheels 38 are moved towards the wheels 18 until the wheels 32 reach the position previously described. Obviously, the cylinder 40 can be actuated in any desired amount so that the wheels 32 may be positioned in accordance with the operator's desire.

A pair of stationary channel members 42 are welded to the main frame of the lift truck l0 and the wheels 38 ride within the channels thereof.

The wheels 32 and the wheels 18 are each provided with selective brakes, as at 33 and 19 respectively, so that the operation of the cylinders 40 can be utilized either to retract the load toward the vehicle, or to pull the entire truck body forward towards the load.

Referring now to FIGS. 4-7, the operation of the vehicle can best be described as follows:

The truck ID with a load 55 on its forks, and the load wheels 32 extended to the optimum wheelbase, is brought to a stop at a given point with the load wheels 32 slightly beyond the opening into which the load is to be positioned. At this position the load is centered on the lift truck forks 30.

As shown in FIG. 5 the operator then turns the truck and the load so that the outboard corner of the load just clears the far side. He then continues the pivot until the truck is in line with the area into which the load is to be stored. The vehicle has now reached the position shown in FIG. 6.

The operator then sets the steering for straight ahead travel, and sets the brakes 33 located in the nonsteerable load wheels 32. With these brakes set, the hydraulic cylinders 40 that control the load arms are actuated, moving the entire truck body, mast, carriage, and load forward and into the load storage area. The sideshifter carriage 28 may then be actuated by the operator to center the load within the storage area, so that the vehicle and load attain the positions shown in FIG. 7.

In order to leave the load in the storage area, the forks are lowered to deposit the load and the hydraulic cylinders on the load arms are extended, causing the truck body, mast, car riage, and forks to move rearwardly. The operator may then turn the steerable wheels, release the brakes on the wheels 32, move the truck back to its original position and proceed to another location. Alternatively, the operator may simply drive the truck out of the space in a manner similar to well-known forklift trucks without extensible anns.

The removal of a load from the storage area requires the above sequence of events to be reversed.

Thus the applicants have provided a narrow-aisle truck which may be utilized in spaces far narrower than those presently required by available lift trucks. It is realized, of course, that although the above description and the drawings have been directed towards a single embodiment of the invention, those skilled in the art will readily see a variety of modifications thereto, without exceeding the purview of the following claims.

We claim:

1. A load-carrying truck comprising a self-propelled chassis having at least one steerable wheel thereon, wheel base changing means comprising a pair of arms retractably mounted on said chassis and on which are rotatably fixed a pair of nonsteerable wheels, a pair of lifting forks vertically movably mounted on said chassis, means fixed to the chassis for extending and retracting the arms, and brake means associated with both steerable and nonsteerable wheels so that when either the steerable or nonsteerable wheels are braked, the nonbraked wheels are moved toward the braked wheels when the extending and retracting means is actuated.

2. The truck of claim 1 including a sideshifter carriage to which the forks are fastened so that they may be moved in a direction perpendicular to the truck's longitudinal axis.

3. The truck of claim 1 wherein the number of steerable wheels is two.

4. A load-carrying truck comprising a self-propelled chassis defining front and rear ends, at least one steerable wheel on the rear end of said chassis, a pair of arms retractably mounted on the front end of said chassis, a pair of nonsteerable wheels mounted on said arms, mast means mounted on the front end of said chassis and vertically, movably supporting load forks, means for extending and retracting said arms whereby the truck wheelbase may be changed, and brake means associated with both steerable and nonsteerable wheels so that when either the steerable or nonsteerable wheels is braked, the nonbraked wheels are moved toward the braked wheels when the extending and retracting means is actuated thereby moving the chassis to the braked wheels.

5. The truck of claim 4 wherein the mast means comprises a pivotally mounted mast, a sideshifter carriage and means to sideshift said carriage.

6. The truck of claim 4 wherein the number of steerable wheels is two.

I 7. The truck of claim 4 wherein the means for extending and retracting the anus comprises hydraulic means.

3 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, ,953 Dated November 2, 1971 ln fl WALTER M. SHAFFER JOHN T. CRAWFORD It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim last line, --re1ative-- should appear after "chassis".

Signed and scaled this 16th day of May 1972.

(SEAL) 1 Aboest:

EDWARD I'LFLETCHER,JR. ROBERT GOTTSCHALK Attesbing; Officer Commissioner of Patents 

1. A load-carrying truck comprising a self-propelled chassis having at least one steerable wheel thereon, wheel base changing means comprising a pair of arms retractably mounted on said chassis and on which are rotatably fixed a pair of nonsteerable wheels, a pair of lifting forks vertically movably mounted on said chassis, means fixed to the chassis for extending and retracting the arms, and brake means associated with both steerable and nonsteerable wheels so that when either the steerable or nonsteerable wheels are braked, the nonbraked wheels are moved toward the braked wheels when the extending and retracting means is actuated.
 2. The truck of claim 1 including a sideshifter carriage to which the forks are fastened so that they may be moved in a direction perpendicular to the truck''s longitudinal axis.
 3. The truck of claim 1 wherein the number of steerable wheels is two.
 4. A load-carrying truck comprising a self-propelled chassis defining front and rear ends, at least one steerable wheel on the rear end of said chassis, a pair of arms retractably mounted on the front end of said chassis, a pair of nonsteerable wheels mounted on said arms, mast means mounted on the front end of said chassis and vertically, movably supporting load forks, means for extending and retracting said arms whereby the truck wheelbase may be changed, and brake means associated with both steerable and nonsteerable wheels so that when either the steerable or nonsteerable wheels is braked, the nonbraked wheels are moved toward the braked wheels when the extending and retracting means is actuated thereby moving the chassis to the braked wheels.
 5. The truck of claim 4 wherein the mast means comprises a pivotally mounted mast, a sideshifter carriage and means to sideshift said carriage.
 6. The truck of claim 4 wherein the number of steerable wheels is two.
 7. The truck of claim 4 wherein the means for extending and retracting the arms comprises hydraulic means. 